Chair

ABSTRACT

A chair includes: a leg body; a backrest supporting body supported by the leg body; and a backrest supporting body supported by the backrest supporting body and configured to support the back of a user. The backrest supporting body has: a backrest which has a flexible upholstering material member that receives the back of the user and enables displacement depending on the back and a pair of vertical frame sections on which the upholstering material member is mounted and which are separated in a width direction in which the vertical frame sections are elastically deformable by a force applied from the upholstering material member; and a backrest rear section supporting member configured to connect the vertical frame sections—in an upward/downward direction.

TECHNICAL FIELD

The present invention relates to a chair.

Priority is claimed on Japanese Patent Applications No. 2012-230929, filed on Oct. 18, 2012, the contents of which are incorporated herein by reference.

BACKGROUND ART

A chair is basically made up of a leg body, a seat section that is provided above the leg body, and a back section that supports a user seated on the seat section, and various constitutions thereof are generally known.

For example, a chair having, as a support structure of the back section of the chair, a back member and arms that extend upward from a leg body and support portions separated on a back surface of the back member in a width direction from a rear side is also proposed (see Patent Document 1 below).

In addition, a chair equipped with a backrest having: a back frame including an upper frame section, a lower frame section, a left frame section, and a right frame section and a back plate that is provided on the inside of the back frame; and a back strut supporting the left and right frame sections of the backrest from a rear side is proposed (see Patent Document 2 below).

In the chair, the back plate can reliably support the back of the user via the back frame supported by the back strut.

CITATION LIST Patent Document Patent Document 1

U.S. Pat. No. 7,249,802

Patent Document 2

Japanese Unexamined Patent Application, First Publication No. 2009-112729

SUMMARY OF INVENTION Technical Problem

However, in the constitution described in Patent Document 1 above, even if a backward force from the user is applied to the back member, the back member is reliably supported by an axial force of the arms, and deformation of the back member in an out-of-plane direction is limited. Accordingly, even if the user assumes a posture in which they recline their back, deformation to an extent that the user can greatly recline their back is difficult.

In addition, in the constitution described in Patent Document 2 above, since the back strut supports the left frame section and the right frame section, even if a backward force from the user is applied to the back plate, deformation of the left and right frame sections is restricted, and deformation of the back plate installed on the left and right frame sections is also restricted. Accordingly, even if the user assumes a posture in which they recline their back, deformation to an extent that the user can greatly recline their back is difficult. For this reason, in the chairs described in Patent Documents 1 and 2, there is a problem that the user cannot freely perform a motion of greatly reclining their back while seated and it is impossible for the chair to follow a change in the user's position.

The present invention has been made keeping in mind the above circumstances and provides a chair capable of following a motion in which a user reclines their back when they perform such a motion.

Solution to Problem

(1) According to a first aspect of the present invention, a chair that includes: a leg body; a backrest supporting body supported by the leg body; a backrest body supported by the backrest supporting body and configured to support a back of a user. The backrest body has: a backrest which has a flexible upholstering material member that receives the back of the user and enables displacement depending on the position of the back and a pair of vertical frame sections on which the upholstering material member is mounted and which are separated in a width direction in which the vertical frame sections are elastically deformable by a force applied from the upholstering material member; and a backrest rear section supporting member configured to connect the vertical frame sections in an upward/downward direction.

According to the aforementioned constitution, a load applied backward to the upholstering material member from the user is transmitted to the pair of vertical frame sections that are mounted on the upholstering material member and are separated in the width direction. The vertical frame sections are elastically deformed to be inclined backward by a force applied from the upholstering material member, and the upholstering material member mounted between the vertical frame sections moves backward in its entirety in the width direction. Also, since the backrest rear section supporting member is connected to the vertical frame sections in the upward/downward direction, the backrest rear section supporting member also assumes the posture of backward inclination along with the backward inclination of the vertical frame sections. Accordingly, when a load of the user is applied in a direction in which a backrest is reclined, the entire backrest can be inclined backward following a motion of reclining the backrest body.

(2) In the chair of (1) above, the backrest is supported by the backrest rear section supporting member and supports the back of the user. The backrest rear section supporting member is supported by the backrest supporting body. The backrest rear section supporting member may have a lower connection section, a deformable section, and an upper connection section. The lower connection section is connected to the backrest supporting body. The deformable section extends upward from the lower connection section and enables elastic deformation depending on a load applied to the backrest from the back of the user. The upper connection section extends upward from an upper end of the deformable section and is connected to the backrest at an upper end thereof.

According to the aforementioned constitution, when a load is applied backward to the backrest from the user, the load of the user is transmitted to the backrest rear section supporting member supporting the backrest. In this case, the deformable section of the backrest rear section supporting member which is interposed between the lower connection section connected to the backrest supporting body and the upper connection section connected to the backrest is elastically deformed to be gradually inclined backward toward the upper side. Along with the deformation of the deformable section, a posture of the backrest supported by the backrest rear section supporting member can be greatly inclined backward.

In addition, the upper connection section is provided above the deformable section inclined backward. Accordingly, as the deformable section is inclined backward, the upper connection section can move backward while an upper end remains connected to the backrest. Therefore, when the load of the user is applied in a direction in which the backrest is reclined, the backrest can be inclined backward following a motion of reclining the backrest.

(3) In the chair of (2) above, the upper connection section may be formed to be gradually inclined forward toward an upper side.

According to the above constitution, since the upper connection section is formed to be gradually inclined forward toward the upper side, it is possible to limit the deformation of the upper connection section itself in the forward/backward direction and to support the load of the user, and the backrest connected to the upper connection section can also reliably support the load of the user.

On the other hand, the deformable section is deformed. Thereby, the backrest connected to the lower and upper connection sections of the backrest rear section supporting member can be inclined backward depending on the load of the user.

(4) In the chair of (2) or (3) above, the upper connection section may have a pair of connection segments that are connected with the deformable section at lower ends thereof, are formed in a V shape so as to be separated from each other toward the upper side, and have upper ends connected to the backrest.

According to the above constitution, the pair of connection segments have upper ends connected to the backrest. Thereby, a load applied to one side or the other side of the backrest from the user in the width direction can be reliably supported.

(5) In the chair described in any one of (2) to (4) above, the vertical frame section may have: a lower material member that has a lower end connected to the lower connection section and is formed to be gradually inclined forward toward the upper side; and an upper material member that extends upward from the lower material member, is formed to be relatively inclined backward relative to the lower material member toward the upper side, and is connected to the upper connection section at an upper end thereof.

According to the above constitution, since the lower material member is inclined forward toward the upper side, it is possible to limit the deformation of the lower material member itself and to support the load of the user. On the other hand, since the upper material member is relatively inclined backward relative to the lower material member toward the upper side, it can follow backward inclination depending on the load of the user.

Here, the vertical frame section connected to the backrest rear section supporting member at upper and lower portions thereof is configured to be inclined within a range of the upper material member in the upward/downward direction. Accordingly, when the backrest rear section supporting member is inclined backward, the upper material member is configured to be inclined at a greater angle of inclination than the backrest rear section supporting member.

For this reason, the vertical frame section can be greatly inclined backward and more effectively follow the back of the user while an amount of deformation of the deformable section of the backrest rear section supporting member is limited to the minimum. Accordingly, even when the deformation of the deformable section is repeated and moment is concentrated, there is no fear of damage or breakage.

(6) In the chair of (5) above, the upholstering material member may have a lower portion connected to the lower material member and an upper portion connected to the upper material member.

According to the above constitution, when the load is applied to the backrest from the user, the upholstering material member of the backrest is deformed along the back of the user, and the deformable section of the backrest rear section supporting member which supports the backrest is elastically deformed. Accordingly, when the load of the user is applied in a direction in which the backrest is reclined, the backrest can be inclined backward following a motion of reclining the backrest and receive the back of the user so as to wrap around the back of the user in the state in which it is inclined backward.

Advantageous Effects of Invention

According to the aforementioned chair, when a user performs a motion of reclining their back, the chair can follow the motion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a chair according to an embodiment of the present invention when viewed from the oblique front side.

FIG. 2 is a perspective view of an upper portion of the chair according to the embodiment of the present invention when viewed from behind.

FIG. 3A is a side view of the chair according to the embodiment of the present invention at normal times.

FIG. 3B is a side view of the chair according to the embodiment of the present invention when a user reclines their back.

FIG. 4 is a perspective view of the chair according to the embodiment of the present invention when viewed from the front.

FIG. 5 is a side view of the chair according to the embodiment of the present invention.

FIG. 6A is a sectional view of the chair according to the embodiment of the present invention taken along line P-P of FIG. 4 at normal times.

FIG. 6B is a sectional view taken along line P-P of FIG. 4 in a state in which the user is seated in the chair according to the embodiment of the present invention.

FIG. 7A is a perspective view of the chair according to the embodiment of the present invention at normal times.

FIG. 7B is a perspective view of the chair according to the embodiment of the present invention when a state in which the user assumes a posture in which they looks back from one side in a width direction to a rear side is viewed from the top.

FIG. 8 is a perspective view of an upper portion of a chair according to a modification of the embodiment of the present invention when viewed from behind.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a chair according to an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the chair 1 according to the present embodiment is equipped with a leg body 10, a backrest supporting body 20, a seat section 30, a backrest rear section supporting member 40, and a backrest 50.

The leg body 10 is provided on a floor F. The backrest supporting body 20 is supported by the leg body 10. The seat section 30 is provided on the backrest supporting body 20 and enables a user to be seated thereon. The backrest rear section supporting member 40 is supported by the backrest supporting body 20. The backrest 50 is supported by the backrest rear section supporting member 40 and supports the back of the user. Details of each component will be described below. Note that, in the following description, a direction in which the user sits or stands up is defined as a forward/backward direction, a side on which the user sits is defined as a front side, and the opposite side is defined as a rear side. In addition, a direction that is perpendicular to the forward/backward direction within a horizontal plane is defined as a width direction, and sides that are separated from the chair in the width direction are defined as lateral sides.

Leg Body

The leg body 10 is equipped with a plurality of leg rods 12 for which casters 11 capable of swiveling on the floor F are provided and a leg column 13 supported by the plurality of leg rods 12. The plurality of leg rods 12 are radially disposed and connected to each other at base ends thereof, and the casters 11 are mounted on respective tips thereof.

The leg column 13 is connected to the base ends of the plurality of leg rods 12 at a lower portion thereof and is erected upward. Also, a support base 14 in which a reclining mechanism (not shown) enabling the backrest supporting body 20 to be inclined backward is housed is mounted on an upper portion of the leg column 13.

Backrest Supporting Body

The backrest supporting body 20 has a pair of forward arm sections 21 whose base parts are pivoted on both lateral sides of the support base 14 in a width direction, a pair of upward arm sections 22 that extend upward from the base parts of the forward arm sections 21 and support the seat section 30, and a pair of backward arm sections 23 that extend backward from the base parts of the forward arm sections 21.

As shown in FIG. 2, the pair of backward arm sections 23 are disposed to gradually approach each other toward the rear side and are connected to each other at rear ends thereof, thereby being disposed in a downward V shape as one body. The rear ends of the pair of backward arm sections 23 are fixed to a lower portion of the backrest rear section supporting member 40 to be described below.

In addition, as shown in FIG. 1, the backrest supporting body 20 is provided with armrests 26 extending upward from the lateral sides thereof.

Seat Section

As shown in FIGS. 3A and 3B, the seat section 30 has a front portion supported to be slidable relative to the support base 14 in the forward/backward direction, and is pivoted on the upward arm sections 22 of the backrest supporting body 20. As the backrest supporting body 20 is inclined backward by the reclining mechanism of the support base 14, the seat section 30 is configured to move backward relative to the support base 14 and to tilt the rear side downward.

Backrest Rear Section Supporting Member

As shown in FIG. 2, the backrest rear section supporting member 40 has a lower connection section 41 connected to the backrest supporting body 20, a deformable section 42 extending upward from the lower connection section 41, and an upper connection section 43 which gradually widens outward in the width direction toward the upper side from an upper end of the deformable section 42.

The lower connection section 41 is formed with a recessed portion (not shown) in a lower rear surface thereof into which the pair of backward arm sections 23 of the backrest supporting body 20 are fitted. The pair of backward arm sections 23 are fitted into the recessed portion. The lower connection section 41 is fixed by, for instance, bolts and nuts (not shown) onto an upper portion of the backrest supporting body 20 at the recessed portion. Further, the lower connection section 41 is connected to the backrest 50 at a lower end thereof.

As shown in FIGS. 1, 4 and 5, the deformable section 42 is connected to the lower connection section 41 at a lower end thereof, is disposed upward, and is connected to the upper connection section 43 at an upper end thereof. The deformable section 42 is also formed such that a length dimension in the width direction gradually decreases toward the upper side and the length dimension in the width direction increases again halfway toward the upper side.

The deformable section 42 is configured to facilitate elastic deformation depending on a load applied to the backrest 50 from the back of the user with no ribs formed on a front surface thereof.

Even when ribs are provided on the surface of the deformable section 42, the deformable section 42 can be configured to enable the elastic deformation depending on the load applied to the backrest from the back of the user by adjusting, for instance, a material member or a thickness thereof.

The upper connection section 43 is connected to the deformable section 42 at a lower end thereof and is formed to gradually widen outward in the width direction toward the upper side and to be gradually inclined forward toward the upper side.

In the present embodiment, the upper connection section 43 has a pair of connection segments 43A and 43B that are disposed to be gradually separated from each other in the width direction toward the upper side and have upper ends connected to the backrest 50. The pair of connection segments 43A and 43B are formed in a V shape as a whole.

The lower connection section 41, the deformable section 42, and the pair of connection segments 43A and 43B constituting the upper connection section 43 are integrally formed, and the backrest rear section supporting member 40 is curved and formed to become convex backward as a whole when viewed from the side.

That is, the lower connection section 41 is curved and inclined upward and backward as a whole. Also, the pair of connection segments 43A and 43B constituting the upper connection section 43 are curved and inclined upward and forward. The deformable section 42 is curved and connects the upper connection section 43 and the lower connection section 41.

Backrest

As shown in FIG. 2, the backrest 50 has an upholstering material member 51 that receives the back of a user, an upper frame section 52 on which the upholstering material member 51 is mounted and which is connected with the upper connection section 43 in the backrest rear section supporting member 40, and a pair of vertical frame sections 53A and 53B (53) which are connected with the upper frame section 52 and on which the upholstering material member 51 is mounted.

The upholstering material member 51 receives the back of the user and is configured of a flexible member that is deformable depending on a position of the back. To be specific, in the present embodiment, the upholstering material member 51 is formed of a mesh-like material, and can be elastically bent and deformed as a whole as threads constituting the mesh elastically expand and contract. The upholstering material member 51 is provided for a portion surrounded by the upper frame section 52 and the pair of vertical frame sections 53 and has an end fixed to the upper frame section 52 and the pair of vertical frame sections 53.

The upper frame section 52 extends in the width direction, and respective ends thereof are connected to upper ends of the pair of connection segments 43A and 43B in the upper connection section 43 and upper ends of the pair of vertical frame sections 53A and 53B.

One vertical frame section 53A has a lower material member 57A and an upper material member 56A that is connected to an upper end of the lower material member 57A and is elastically deformable by the force applied from the upholstering material member 51. Similarly, the other vertical frame section 53B also has a lower material member 57B and an upper material member 56B that is connected to an upper end of the lower material member 57B and is elastically deformable by the force applied from the upholstering material member 51.

As shown in FIGS. 2 and 5, the lower material members 57A and 57B are connected to the lower connection section 41 of the backrest rear section supporting member 40 at lower ends thereof and are formed to be gradually directed forward toward the upper side and to gradually widen outward in the width direction toward the upper side. Each of the lower material members 57A and 57B is also formed such that cross-sectional dimensions are reduced toward the upper side.

The upper material members 56A and 56B are configured to elastically enable twisting deformation and bending deformation depending on the load applied by the back of the user.

The upper material members 56A and 56B are connected to the lower material members 57A and 57B corresponding thereto at lower ends thereof, connected to the upper frame section 52 and the pair of connection segments 43A and 43B of the backrest rear section supporting member 40 at upper ends thereof, and formed to be inclined backward relative to the lower material members 57A and 57B toward the upper side.

In the present embodiment, the upper material members 56A and 56B are formed to be gradually inclined backward from the upper ends of the lower material members 57A and 57B toward the upper side.

In this way, the vertical frame sections 53A and 53B are formed by the lower material members 57A and 57B so as to turn upward and gradually forward from lower portions thereof and are formed by the upper material members 56A and 56B so as to turn upward and gradually forward from connected portions of the lower material members 57A and 57B and the upper material members 56A and 56B. The vertical frame sections 53A and 53B are also curved to become convex forward as a whole.

As shown in FIG. 2, the backrest rear section supporting member 40 and the vertical frame section 53 are integrally formed in an annular shape when viewed from the side. In the present embodiment, the lower connection section 41, the deformable section 42, and one connection segments 43A of the backrest rear section supporting member 40 and the upper material member 56A and the lower material member 57A of one vertical frame section 53A constitute a first annular section 61 having an annular shape when viewed from the side.

In addition, a second annular section 62 having an annular shape when viewed from the side is configured by the lower connection section 41, the deformable section 42, and the other connection segments 43B of the backrest rear section supporting member 40 and by the upper material member 56B and the lower material member 57B of the other vertical frame section 53B.

These first and second annular sections 61 and 62 are connected by the lower connection section 41 and the deformable section 42 and are integrally formed as a whole. The upper frame section 52 is also integrally formed to connect an upper end of each of the first and second annular sections 61 and 62.

That is, in the present embodiment, each section of the backrest rear section supporting member 40 and the upper frame section 52 and the pair of vertical frame sections 53A and 53B of the backrest 50 are integrally formed.

In addition, a backrest body 50A is configured by the backrest rear section supporting member 40 and the backrest 50. That is, the backrest body 50A is supported by the backrest supporting body 20 and supports the back of the user.

Next, motions of the backrest rear section supporting member 40 and the backrest 50 of the chair 1 when a user is seated on the seat section 30 of the chair 1 configured as described above will be described.

A solid line of FIG. 4 and FIG. 6A show the chair 1 in a state in which the user is seated on the seat section 30 and does not lean against the backrest 50, and a chain double dashed line of FIG. 4 and FIG. 6B show the chair 1 in a state in which the user leans against the backrest 50.

When the user is seated on the seat section 30, a force from the user is applied to the upholstering material member 51 of the backrest 50. As the threads constituting the mesh of the upholstering material member 51 elastically expand and contract due to this force, approximately the middle of the upholstering material member 51 in the width direction is elastically deformed in a circular arc shape so as to protrude backward along the back of the user as a whole.

Due to a force applied from the upholstering material member 51, the vertical frame sections 53A and 53B to which the upholstering material member 51 is fixed are elastically deformed to direct inner sides thereof in the width direction to the rear side and move to the inner sides thereof in the width direction so as to approach each other.

As the vertical frame sections 53A and 53B are elastically deformed, the upholstering material member 51 can be further deformed in a circular arc shape in which approximately the middle thereof protrudes backward, and the backrest 50 is supported by the backrest rear section supporting member 40.

Further, when the user greatly leans against the backrest 50, the deformable section 42 of the backrest rear section supporting member 40 connected to the vertical frame sections 53A and 53B, as indicated by a chain double dashed line of FIG. 5, can be elastically deformed depending on the load applied from the back of the user to the backrest 50. Accordingly, the deformable section 42 is deformed to be gradually inclined backward toward the upper side centering on the lower end thereof. Along with the deformation of the deformable section 42, the upper connection section 43 disposed on an upper side of the deformable section 42 moves backward, and the backrest 50 connected to the upper connection section 43 can be further inclined backward.

In addition, when the user assumes a position in which they look back from one side of the backrest 50 in the width direction to the rear side from the state shown in FIG. 7A, the load from the user is, as shown in FIG. 7B, applied with bias toward the one side of the backrest 50 in the width direction, and a load causing twisting deformation of the vertical frame section 53B is applied to the vertical frame section 53B of the biased side.

Here, the upper material member 56B in the vertical frame section 53B is configured to enable twisting deformation by the force applied from the backrest 50. The connection segments 43A and 43B are also formed to reduce the width to be separated toward the lower side, joined to each other, and connected to the deformable section 42. Thus, the deformable section 42 is configured to facilitate the twisting deformation of the upper material member 56B. Accordingly, the upper material member 56B is twisted and deformed toward a rear lateral side so as to follow the back of the user depending on the load of the user.

In addition, the connection segments 43B connected to the upper material member 56B is configured to be displaceable with the twist of the upper material member 56B, and thus is displaced to a rear lateral side with the twist turning to a rear lateral side of the vertical frame section 53B.

The upholstering material member 51 in the backrest 50 is elastically deformed such that the threads constituting the mesh of the upholstering material member 51 elastically expand and contract to wrap around the back of the user due to the load from the user.

In this way, the upper material member 56B, the connection segment 43B, and the upholstering material member 51 are deformed to follow deformation of the back and shoulders of the user to wrap around the back and shoulders.

Even when the user assumes a posture in which they looks back from the other side of the backrest 50 in the width direction to the rear side, the same motion is performed.

In the chair 1 configured in this way, when the load is applied backward from the user to the backrest 50, the load of the user is transmitted to the upper connection section 43 of the backrest rear section supporting member 40 supporting the upper frame section 52 of the backrest 50. In this case, the deformable section 42 of the backrest rear section supporting member 40 interposed between the lower connection section 41 connected to the backrest supporting body 20 and the upper connection section 43 connected to the backrest 50 is elastically deformed so as to be gradually inclined backward toward the upper side. Along with the deformation of the deformable section 42, a posture of the backrest 50 supported by the backrest rear section supporting member 40 can be greatly inclined backward.

The upper connection section 43 is also provided at the upper side relative to the deformable section 42 inclined backward. Accordingly, as the deformable section 42 is inclined backward, the upper connection section 43 can move backward while the upper end thereof remains connected to the backrest 50. Thus, when the load of the user is applied in a direction in which the backrest is reclined, the backrest 50 can be inclined backward following a motion of reclining the backrest 50.

In a normal state, the upper connection section 43 is formed to be gradually inclined forward toward the upper side. Thus, it is possible to limit the deformation of the upper connection section 43 itself to support the load of the user in the forward/backward direction, and the backrest 50 connected to the upper connection section 43 can also reliably support the load of the user.

On the other hand, when the user causes a load greater than in the normal state to be applied to the backrest backward in order to recline their back, the deformable section 42 is deformed by the load. Thereby, the backrest 50 connected to the lower and upper connection sections 41 and 43 of the backrest rear section supporting member 40 can be inclined backward depending on the load of the user, and follow a motion of the user inclining their back.

Meanwhile, the pair of connection segments 43A and 43B of the upper connection section 43 are connected to the backrest 50 at the upper ends thereof, and thereby can reliably support the load applied to the one side or the other side of the backrest 50 in the width direction.

Since the lower material members 57A and 57B are inclined forward toward the upper side, it is possible to limit the deformation of the lower material members 57A and 57B themselves and to reliably support the load of the user.

On the other hand, since the upper material members 56A and 56B are formed to be gradually inclined backward toward the upper side from the upper ends of the lower material members 57A and 57B, they can be inclined backward depending on the load of the user and follow the motion of the user reclining their back.

Here, in the backrest 50 connected to the lower and upper connection sections 41 and 43 of the backrest rear section supporting member 40 at the lower and upper portions thereof, the deformation of the lower material members 57A and 57B is limited, and the backrest 50 is configured to be inclined within a range of the upper material members 56A and 56B in the upward/downward direction. Accordingly, when the backrest rear section supporting member 40 is inclined backward, the upper material members 56A and 56B are configured to be inclined at an oblique angle greater than that of the backrest rear section supporting member 40.

For this reason, the backrest 50 can be greatly inclined backward and more effectively follow the back of the user while an amount of the deformation of the deformable section 42 of the backrest rear section supporting member 40 is limited to the minimum. Accordingly, even when the deformation of the deformable section 42 is repeated and moment is concentrated, there is no fear of damage or breakage.

With respect to the force applied backward from the user, when the back of the user is received by the upholstering material member 51 of the backrest 50, the load of the user is transmitted from the upholstering material member 51 to the upper frame section 52 and the pair of vertical frame sections 53A and 53B. The upper frame section 52 is connected to and supported by the pair of connection segments 43A and 43B of the backrest rear section supporting member 40, and the backrest rear section supporting member 40 is supported by the backrest supporting body 20. Accordingly, the load from the user can be reliably supported by the upper frame section 52, the backrest rear section supporting member 40, and the backrest supporting body 20.

On the other hand, since the upper material members 56A and 56B of the pair of vertical frame sections 53A and 53B which are connected to both ends of the upper frame section 52 in the width direction are elastically bent and deformed by the force applied from the upholstering material member 51, they can be deformed to follow the back of the user depending on the load of the user and be received to wrap around the back along with the upholstering material member 51. For this reason, the user can sit in a stable state.

Further, when the user assumes a posture in which they look back from the one side in the width direction to the rear side, the load of the user is applied with bias toward the one side of the backrest 50 in the width direction, and the load causing twisting deformation of the vertical frame section 53A or 53B is applied to the vertical frame section 53A or 53B of the biased side. Since the upper material member 56A or 56B of the vertical frame section 53A or 53B is subjected to the twisting deformation by the force applied from the upholstering material member 51, the upholstering material member 51 can be deformed to follow deformation of the back and shoulders of the user, receive the back so as to wrap around the back along with the upholstering material member, and incline the backrest 50 backward.

Also, when the load from the user is transmitted from the upholstering material member 51 of the backrest 50 to the pair of vertical frame sections 53A and 53B, the upper material members 56A and 56B of the vertical frame section 53A or 53B are subjected to the twisting deformation. The pair of connection segments 43A and 43B connected to the upper material members 56A and 56B are displaced along with the twisting deformation of the upper material members 56A and 56B. Accordingly, when the user assumes a posture in which they look back from the one side in the width direction to the rear side, one of the upper material members 56A and 56B undergoes the twisting deformation, and one of the connection segments 43A and 43B is displaced. One of the upper material members 56A and 56B and one of the connection segments 43A and 43B can receive the back so as to wrap around the back along with the upholstering material member, and thus stably support the back and shoulders of the user while following the deformation.

In this way, the upper material members 56A and 56B of the vertical frame sections 53A and 53B, the upholstering material member 51, and the connection segments 43A and 43B can follow the deformation of the back and shoulders of the user to stably support the back and shoulders while being inclined backward.

On the other hand, the lower material members 57A and 57B of the vertical frame sections 53A and 53B reliably support the circumference of the waist below the back of the user with the upholstering material member 51. Accordingly, when the user assumes a posture in which they look back from the one side in the width direction to the rear side, the lower material members 57A and 57B can support the circumference of the waist of the user along with the upholstering material member 51.

Modification

Next, a chair 101 according to a modification of the embodiment represented above will be described using FIG. 8.

In the chair 1, the pair of backward arm sections 23 and 23 of the backrest supporting body 20 are connected to the lower portion of the backrest rear section supporting member 40. On the other hand, in the chair 101 according to the modification, a pair of backward arm sections 123 and 123 of a backrest supporting body 120 are connected to lower material members 57A and 57B of a pair of vertical frame sections 53A and 53B. That is, the vertical frame sections 53A and 53B are supported by the backrest supporting body 120.

To be specific, similar to the lower material members 57A and 57B, upper portions of backward arm sections 123 and 123 are formed to be gradually directed forward toward an upper side. The upper portions of the backward arm sections 123 and 123 and the lower material members 57A and 57B are connected.

Also, a recessed portion on which the pair of backward arm sections 123 and 123 are mounted is formed in a surface of a lower connection section 141 of a backrest rear section supporting member 140.

In the chair 101 configured in this way, a load applied backward to an upholstering material member 51 from a user is transmitted to a pair of vertical frame sections 53A and 53B that are mounted on the upholstering material member 51 and are separated in the width direction. The vertical frame sections 53A and 53B are elastically deformed to be inclined backward by the force applied from the upholstering material member 51, and the upholstering material member 51 mounted between the vertical frame sections 53A and 53B moves backward throughout the entire width direction. In addition, since the backrest rear section supporting member 140 is connected to the vertical frame sections 53A and 53B in the upward/downward direction, the backrest rear section supporting member 140 also inclines the posture backward along with the backward inclination of the vertical frame sections 53A and 53B. Accordingly, when a load of the user is applied in a direction in which a backrest 50 is reclined, the entire backrest 50 can be inclined backward following a motion of reclining a backrest body 50A.

Also, similar to the embodiment represented above, when the user is seated on a seat section 30 of the chair 101, a force from the user is applied to the upholstering material member 51 of the backrest 50, and threads constituting a mesh of the upholstering material member 51 elastically expand and contract due to the force. Thereby, approximately the middle of the upholstering material member 51 in the width direction is elastically deformed in a circular arc shape so as to protrude backward along the back of the user as a whole.

Due to a force applied from the upholstering material member 51, the vertical frame sections 53A and 53B to which the upholstering material member 51 is fixed are elastically deformed to direct inner sides thereof in the width direction to a rear side and move to the inner sides thereof in the width direction so as to approach each other.

As the vertical frame sections 53A and 53B are elastically deformed, the upholstering material member 51 can be further deformed in a circular arc shape in which approximately the middle thereof protrudes backward, and the backrest 50 is supported by the backrest rear section supporting member 140.

In addition, similar to the embodiment represented above, when the user assumes a posture in which they looks back from one side of the backrest 50 in the width direction to the rear side, the load from the user is applied with bias toward the one side of the backrest 50 in the width direction, and a load causing twisting deformation of the vertical frame section 53A or 53B is applied to the vertical frame section 53A or 53B of the biased side. Since upper material members 56A and 56B of the vertical frame sections 53A and 53B are subjected to twisting deformation by the force applied from the upholstering material member 51, they are deformed to follow deformation of the back and shoulders of the user depending on the load of the user, receive the back so as to wrap around the back along with the upholstering material member, and enable the backrest 50 to be inclined backward.

Also, a pair of connection segments 43A and 43B connected to the upper material members 56A and 56B of the vertical frame sections 53A and 53B are displaced along with the twisting deformation of the upper material members 56A and 56B. Accordingly, when the user assumes a posture in which they looks back from the one side in the width direction to the rear side is taken, the upper material member 56A or 56B of the one side undergoes the twisting deformation, and the connection segment 43A or 43B of the one side is displaced. The upper material member 56A or 56B and the connection segment 43A or 43B can receive the back so as to wrap around the back along with the upholstering material member, and thus stably support the back and shoulders of the user while following the deformation.

In this way, the upper material member 56A or 56B of the vertical frame section 53A or 53B, the upholstering material member 51, and the connection segment 43A or 43B can follow the deformation of the back and shoulders of the user and stably support the back and shoulders while being inclined backward.

On the other hand, the lower material members 57A and 57B of the vertical frame sections 53A and 53B reliably support, for instance, the circumference of the waist below the back of the user along with the upholstering material member 51. Accordingly, when the user assumes a posture in which they looks back from the one side in the width direction to the rear side is taken, the lower material members 57A and 57B can support the circumference of the waist of the user along with the upholstering material member 51.

In addition, the lower material members 57A and 57B and the upper portions of the backward arm sections 123 and 123 connected to the lower material members 57A and 57B are inclined forward toward the upper side. Accordingly, the chair 101 limits the deformation of the lower material members 57A and 57B and the backward arm sections 123 and 123 and reliably supports the load of the user. Also, since the lower material members 57A and 57B and the backward arm sections 123 and 123 inhibit the members from being deformed, they can maintain a firm connection to each other.

In addition, the motion procedures shown in the aforementioned embodiments and all the shapes and combinations of each constituent member are only examples and can be variously modified based on design requirements without departing from the spirit and scope of the present invention.

For example, in the embodiments represented above, the backrest rear section supporting member 40 and the backrest 50 are integrally formed. However, the backrest rear section supporting member 40 and the backrest 50 may also be used as separate members.

INDUSTRIAL APPLICABILITY

According to the aforementioned chair, when the user performs a motion of reclining their back, the chair can follow the motion.

REFERENCE SIGNS LIST

-   -   1, 101 . . . chair     -   10 . . . leg body     -   20, 120 . . . backrest supporting body     -   40, 140 . . . backrest rear section supporting member     -   41, 141 . . . lower connection section     -   42 . . . deformable section     -   43 . . . upper connection section     -   43A, 43B . . . pair of connection segments     -   50 . . . backrest     -   50A . . . backrest body     -   51 . . . upholstering material member     -   52 . . . upper frame section     -   53A, 53B (53) . . . vertical frame section     -   56A, 56B (56) . . . upper material member     -   57A, 57B (57) . . . lower material member     -   61 . . . first annular section     -   62 . . . second annular section 

1. A chair comprising: a leg body; a backrest supporting body supported by the leg body; a backrest body supported by the backrest supporting body and configured to support a back of a user, wherein the backrest body has: a backrest has a flexible upholstering material member that receives the back of the user and enables displacement depending on the back and a pair of vertical frame sections on which the upholstering material member is mounted and which are separated in a width direction in which the vertical frame sections are elastically deformable by a force applied from the upholstering material member; and a backrest rear section supporting member configured to connect the vertical frame sections in an upward/downward direction.
 2. The chair according to claim 1, wherein: the backrest is supported by the backrest rear section supporting member and supports the back of the user; and the backrest rear section supporting member is supported by the backrest supporting body and has: a lower connection section that is connected to the backrest supporting body; a deformable section that extends upward from the lower connection section and enables elastic deformation depending on a load applied to the backrest from the back of the user; and an upper connection section that extends upward from an upper end of the deformable section and is connected to the backrest at an upper end thereof.
 3. The chair according to claim 2, wherein the upper connection section is formed to be gradually inclined forward toward an upper side.
 4. The chair according to claim 2, wherein the upper connection section has a pair of connection segments that are connected to the deformable section at lower ends thereof, are formed in a V shape so as to be separated from each other toward the upper side, and have upper ends connected to the backrest.
 5. The chair according to claim 2 wherein the vertical frame section has: a lower material member that has a lower end connected to the lower connection section and is formed to be gradually inclined forward toward the upper side; and an upper material member that extends upward from the lower material member, is formed to be inclined backward relative to the lower material member toward the upper side, and is connected to the upper connection section at an upper end thereof.
 6. The chair according to claim 5, wherein the upholstering material member has a lower portion connected to the lower material member and has an upper portion connected to the upper material member.
 7. The chair according to claim 3 wherein the upper connection section has a pair of connection segments that are connected to the deformable section at lower ends thereof, are formed in a V shape so as to be separated from each other toward the upper side, and have upper ends connected to the backrest.
 8. The chair according to claim 4 wherein the vertical frame section has: a lower material member that has a lower end connected to the lower connection section and is formed to be gradually inclined forward toward the upper side; and an upper material member that extends upward from the lower material member, is formed to be inclined backward relative to the lower material member toward the upper side, and is connected to the upper connection section at an upper end thereof. 